1. Field of the Invention
The present invention relates to a polyarylenesulfide resin composition which can be used as molding materials for injection-molded articles.
2. Related Art
Polyarylene sulfide (PAS) has been used in a variety of fields as engineering plastics because of its excellent properties such as good heat resistance and good flame resistance.
However, the PAS does not possess enough impact strength. Thus, attempts have been made to improve the impact strength by adding a rubbery material such as natural rubber, NBR or isoprene rubber. The addition of these rubbery materials does not sufficiently contribute to the improvement of the impact strength since such rubbery materials possess double bonds in the molecule, leading to thermal degradation at temperature for blending the PAS.
On the other hand, it has been proposed, in Japanese Patent Application Laid-Open Gazettes No. 63-118,369; 63-161,057; Hei 1-240,566; and Hei2-215,861, to improve impact strength of the PAS by adding as rubbery material a hydrogenated styrene-butadiene-styrene copolymer (SEBS) having an improved thermal degradation property, which is prepared from hydrogenation of a styrene-butadiene-styrene copolymer (SBS).
However, the addition of the SEBS to the PAS has the following drawbacks.
(a) The SEBS has poor solubility to the PAS, resulting in coming off of the surface layer. PA1 (b) Although the solubility of the SEBS is improved by acid modification, decomposed gas derived from acid functional groups will be generated and decrease electrical properties. PA1 (c) The composition consisting of the PAS and the SEBS has poor resistance to gasoline (oil). PA1 (d) Since the SEBS is a thermoplastic elastomer, the addition of the SEBS decreases heat distortion temperature (HDT) of the PAS composition. PA1 (e) The impact strength is somewhat improved by the addition of the SEBS to the PAS. However, due to poor solubility of the SEBS to the PAS, the SEBS cannot be well dispersed in the domain portion, resulting in insufficient improvement effects.
Because of the above drawbacks, it is difficult to sufficiently improve the impact strength of the PAS composition by the addition of the SEBS.